The present invention relates to a method of preparing lactam magnesium salt. Specifically, the present invention relates to a method of preparing lactam magnesium halide by reacting together magnesium, a hydrocarbon halide, and lactam monomer.
Generally, lactam magnesium salts are prepared by adding an ether solution of the Grignard reagent to lactam either in a solvent or in molten form. The solvent is then removed along with the resulting hydrocarbon residue leaving a solution of lactam magnesium salt. Typical Grignard reagents utilized in the process of making lactam magnesium salt are alkyl magnesium halides wherein the alkyl is of a low molecular weight (i.e. ethyl).
The major drawback with the above-described method of preparing lactam magnesium salts is the complicated and involved process of first forming the Grignard reagent and then reacting lactam therewith, and secondly, the difficulty in handling lower alkyl Grignards which are highly exothermically reactive with water and are dangerous to transport.